1. Technical Field
The present invention relates to a system and method for controlling power of a fuel cell to prevent deterioration and performance degradation of the fuel cell, and more particularly, to a system and method for controlling power of a fuel cell to prevent the power from being suddenly changed.
2. Description of the Related Art
To prevent performance deterioration of a fuel cell stack, a high temperature operation region should be avoided. However, even though temperature is maintained in an appropriate range by a cooling control of a fuel cell, the fuel cell may increase to the high temperature operation region due to a limitation of cooling performance. In particular, a method for limiting power may not be able to be used. The present invention proposes a method for optimally limiting power for minimizing a damage of operation characteristics and optimally maintaining performance of the stack, in the method for limiting power at high temperature. In addition to power limit mapping for an operation temperature, prevention of power limit shaking, maintenance of power limit start reference consistency, change in a power limiting reference based on an environment and operation state, and the like will be used.
A fuel cell system is configured to include a hydrogen supply system, an air supply system, and a cooling system and includes a separate fuel cell load apparatus. The cooling system is configured to include a water pump for supplying cooling water, a radiator and a radiator fan for heat radiation of cooling water, and a thermostat for adjusting an amount of water of a radiator loop and a bypass loop. The fuel cell load apparatus is used to prevent a stack voltage from increasing during warm-up of a fuel cell or starting/shut down. The fuel cell load apparatus may be a resistor, a chargeable high voltage battery, or other load apparatuses.
To adjust the temperature of the fuel cell, the radiator fan and the water pump are operated to prevent the stack from increasing to a high temperature (e.g., predetermined temperature) and the warm-up control is performed using the fuel cell load apparatus to prevent the stack from decreasing to particular low temperature. Accordingly, even though a control for preventing the high temperature/low temperature operation is performed, the temperature may not be maintained in acceptable range due to the limitation of cooling and warm-up performance. Consequently, power to temperature is limited and thus, the deterioration (e.g., flooding prevention during low temperature, prevention of high temperature dry-out, prevention of high temperature deterioration, and the like) of the stack is prevented. However, when adjusting the power of the stack based on temperature, the power may be transient, drivability may be reduced, and the deterioration of the fuel cell may not effectively be prevented in advance.
The matters described as the related art have been provided merely for assisting in the understanding for the background of the present invention and should not be considered as corresponding to the related art known to those skilled in the art.